Coherent signal combining with multiple-outputs for quasi-CW LIDAR operation

ABSTRACT

The present disclosure is directed to a coherent signal generator comprising an amplifier configured to receive a plurality of optical signals that are respectively associated with a plurality of phases, and generate a plurality of amplified optical signals using the plurality of optical signals; and a splitter network that is coupled to the amplifier. The splitter network is configured to receive the plurality of amplified optical signals, and generate a combined optical signal at an output of a plurality of outputs using the plurality of amplified optical signals.

CROSS_REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of and priority to U.S. ProvisionalPatent Application No. 62/985,724, filed Mar. 5, 2020 and U.S.Provisional Patent Application No. 62/993,436, filed Mar. 23, 2020, theentire disclosures of each of which are incorporated herein byreference.

BACKGROUND

Optical detection of range using lasers, often referenced by a mnemonic,LIDAR, for light detection and ranging, also sometimes called laserRADAR, is used for a variety of applications, from altimetry, toimaging, to collision avoidance. LIDAR provides finer scale rangeresolution with smaller beam sizes than conventional microwave rangingsystems, such as radio-wave detection and ranging (RADAR). Opticaldetection of range can be accomplished with several differenttechniques, including direct ranging based on round trip travel time ofan optical pulse to an object, and chirped detection based on afrequency difference between a transmitted chirped optical signal and areturned signal scattered from an object, and phase-encoded detectionbased on a sequence of single frequency phase changes that aredistinguishable from natural signals.

SUMMARY

Aspects of the present disclosure relate generally to light detectionand ranging (LIDAR) in the field of optics, and more particularly tosystems and methods for coherent beam combining with multiple-outputsfor quasi-CW LIDAR operation, to support the operation of a vehicle.

BRIEF DESCRIPTION OF THE FIGURES

Implementations are illustrated by way of example, and not by way oflimitation, in the figures of the accompanying drawings in which likereference numerals refer to similar elements and in which:

FIG. 1 is a block diagram illustrating an example of a systemenvironment for autonomous vehicles according to some implementations;

FIG. 2A is a block diagram depicting an example quasi-CW LIDAR systemfor operating of a vehicle, according to some implementations;

FIG. 2B is a block diagram depicting an example quasi-CW LIDAR systemfor operating of a vehicle, according to some implementations;

FIG. 3 is a block diagram depicting an example environment of a coherentsignal generator architecture for coherent signal combining withmultiple-outputs for quasi-CW LIDAR operation, according to someimplementations;

FIG. 4 is a time-based graph depicting quasi-CW waveforms as measured atthe output channels 312 a-312 d of the coherent signal generator in FIG.3, in accordance with an illustrative implementation;

FIG. 5 is a time-based graph depicting the summation of the outputpowers from the SOAs 308 a-308 d of the coherent signal generator inFIG. 3, in accordance with an illustrative implementation;

FIG. 6 is a block diagram depicting the example environment of thecoherent signal generator architecture in FIG. 3 when configured todirect all the light onto an output channel, according to someimplementations;

FIG. 7 is a block diagram depicting the example environment of thecoherent signal generator architecture in FIG. 3 when configured todirect all the light onto an output channel, according to someimplementations;

FIG. 8 is a block diagram depicting the example environment of thecoherent signal generator architecture in FIG. 3 when configured todirect all the light onto an output channel, according to someimplementations;

FIG. 9 is a block diagram depicting the example environment of thecoherent signal generator architecture in FIG. 3 when configured todirect all the light onto an output channel, according to someimplementations; and

FIG. 10 is a block diagram depicting an example environment of acoherent signal generator architecture for coherent signal combiningwith multiple-outputs for quasi-CW LIDAR operation, according to someimplementations.

DETAILED DESCRIPTION

A LIDAR system may include a laser source for providing a light signal(sometimes referred to as, “beam”), one or more modulators formodulating a phase and/or a frequency of the light signal usingContinuous Wave (CW) modulation or quasi-CW modulation, an amplifier foramplifying the modulated signal to send the signal up to a certainrange, and/or optics (e.g., a mirror scanner) for steering the amplifiedsignal to an environment within a given field of view.

In a LIDAR system that uses CW modulation, the modulator modulates thelaser light continuously. For example, if a modulation cycle is 10seconds, an input signal is modulated throughout the whole 10 seconds.Instead, in a LIDAR system that uses quasi-CW modulation, the modulatormodulates the laser light to have both an active portion and an inactiveportion. For example, for a 10 second cycle, the modulator modulates thelaser light only for 8 seconds (sometimes referred to as, “the activeportion”), but does not modulate the laser light for 2 seconds(sometimes referred to as, “the inactive portion”). By doing this, theLIDAR system may be able to reduce power consumption for the 2 secondsbecause the modulator does not have to provide a continuous signal.

In Frequency Modulated Continuous Wave (FMCW) LIDAR for automotiveapplications, it may be beneficial to operate the LIDAR system usingquasi-CW modulation where FMCW measurement and signal processingmethodologies are used, but the light signal is not in the on-state(e.g., enabled, powered, transmitting, etc.) all the time. In someimplementations, Quasi-CW modulation can have a duty cycle that is equalto or greater than 1% and up to 50%. If the energy in the off-state(e.g., disabled, powered-down, etc.) can be expended during the actualmeasurement time then there may be a boost to signal-to-noise ratio(SNR) and/or a reduction in signal processing requirements to coherentlyintegrate all the energy in the longer time scale.

In some implementations, an erbium-doped fiber amplifier (EDFA) may beused to implement a coherent signal generator (e.g., coherent signalgenerator 206 in FIG. 2A, coherent signal generator 206 in FIG. 2B). Byusing an EDFA for the coherent beam generator, for a system implementingquasi-CW modulation as the optical gain and/or energy can be stored andoutput signals from the EDFA can be provided in shorter bursts just bypulsing the input to the EDFA.

In some implementations, semiconductor optical amplifiers (SOAs) can beused to implement a coherent signal generator (e.g., coherent signalgenerator 206 in FIG. 2A, coherent signal generator 206 in FIG. 2B). Byusing SOAs for the coherent signal generator, a high level ofintegration may be achieved. For example, a large number of SOA's can bescaled-down and placed onto a single semiconductor chip, which mayresult in improvements in not only speed (e.g., less latency) and powerconsumption (e.g., the power may be more efficiently routed between theSOAs), but also improvements in the manufacturing process. That is,scaling down the coherent signal generator (sometimes referred to as,“signal processing system”) onto a single semiconductor chip means thatthe semiconductor chip (e.g., silicon) may be smaller in size, therebydecreasing the likelihood of a manufacturing defect affecting theperformance of the coherent signal generator.

Accordingly, the present disclosure is directed to systems and methodsfor coherent signal generating (e.g., combining, merging, adding,mixing, etc.) with multiple-outputs for quasi-CW LIDAR operation, tosupport the operation of a LIDAR system for a vehicle.

In various example implementations, as described in the below passages,a coherent signal generator may include one or more phase shifters,and/or one or more splitters (e.g., 50/50 splitters). The coherentsignal generator may include an amplifier containing multiplesub-amplifiers, such as SOAs, that are each coupled to one or moreoutput channels of the coherent signal generator via one or more beamsplitters (e.g., a 50/50 beam splitter, etc.). Each sub-amplifier mayprovide a continuous wave (e.g., up to 95% duty cycle) having a fixedoutput power. The coherent signal generator may coherently combine(using the one or more splitters) the output powers of some or all ofthe sub-amplifiers into a combined output power, and send the combinedoutput power to one of the output channels. For example, if the coherentsignal generator includes 8 sub-amplifiers that each produce 100milliwatts (mW) of output power, then the coherent signal generatorwould combine the output power from the 8 sub-amplifiers to generate acombined output power of 800 mW, and send the combined output power toone of the output channels.

The power combining may be controlled by specific settings of theoptical phase relationships among all the sub-amplifiers. The phases maybe set (e.g., configured, programmed, initialized, etc.) to provide acombined output power from all the sub-amplifiers in the coherent signalgenerator to one output channel (e.g., 800 mW of output power that isgenerated/combined from 8 sub-amplifiers that each produce 100 mW), acombined output power from some of the sub-amplifiers in the coherentsignal generator to one output channel (e.g., 200 mW of output powerthat is generated/combined from 2 of the 8 sub-amplifiers in thecoherent signal generator that each produce 100 mW), or any combinationin-between. The phases may be set to provide the output power (e.g., 100mW) of any of the sub-amplifiers to any of the output channels.

As the phase settings can be changed rapidly, in some implementations,the architecture of the CNC network allows the full combined outputpower (e.g., 800 mW in an 8 sub-amplifier network) from all thesub-amplifiers to be sent to each of the output channels (e.g., 8channels) sequentially, thereby producing a series of pulses in timeprovided from each output channel. In some implementations, the totalaverage power provided from all the output channels of the coherentsignal generator remains constant, but the distribution of power amongthe output channels may vary in time.

Various example implementations described herein may include one or moreof the following features: (1) some or all paths (from input to output)of the coherent signal generator may be length-matched to ensure stableoperation over temperature; (2) the output powers of some or all of thesub-amplifiers of the one or more splitters may be close to identical toget high contrast on one or more output channels of the coherent signalgenerator; (3) the one or more splitters may have a low-loss and/or veryclose to a 50/50 split ratio; (4) the coherent signal generator mayinclude one or more waveguide crossings, where the coupling to the wrongpath is minimized; the coherent signal generator may include one or moreslow static phase shifters on half the branches of each layer tomaintain stable operation; (5) the coherent signal generator may includea tap photodiode on the output channels and/or selected points along thebranches of the one or more splitters for development purposes and/or toensure stable operation; (6) the coherent signal generator may include atap from a laser source before the one or more modulators for coherentdetection; (7) the coherent signal generator may include one or morephase shifters before the one or more sub-amplifiers; (8) the coherentsignal generator may include one or more phase shifters after the one ormore sub-amplifiers; and (9) the coherent signal generator may includeone or more phase shifters after the one or more sub-amplifiers that arefast enough to implement the switching efficiently and rapidly (e.g.,rise time less than 100 ns), to produce the benefit of losses beingcompensated by the sub-amplifier gain.

The one or more splitters, in some implementations, may be replaced witha multi-mode interference (MMI) structure or coupler. A binary switchnetwork, in some implementations, after the one or more splitters (orthe MIM structure or coupler) may be used to split the outputs to evenmore output channels.

In the following description, for the purposes of explanation, numerousspecific details are set forth in order to provide a thoroughunderstanding of the present disclosure. It will be apparent, however,to one skilled in the art that the present disclosure may be practicedwithout these specific details. In other instances, well-knownstructures and devices are shown in block diagram form in order to avoidunnecessarily obscuring the present disclosure.

1. System Environment for Autonomous Vehicles

FIG. 1 is a block diagram illustrating an example of a systemenvironment for autonomous vehicles according to some implementations.

Referring to FIG. 1, an example autonomous vehicle 100 within which thevarious techniques disclosed herein may be implemented. The vehicle 100,for example, may include a powertrain 102 including a prime mover 104powered by an energy source 106 and capable of providing power to adrivetrain 108, as well as a control system 110 including a directioncontrol 112, a powertrain control 114, and a brake control 116. Thevehicle 100 may be implemented as any number of different types ofvehicles, including vehicles capable of transporting people and/orcargo, and capable of traveling in various environments, and it will beappreciated that the aforementioned components 102-116 can vary widelybased upon the type of vehicle within which these components areutilized.

For simplicity, the implementations discussed hereinafter will focus ona wheeled land vehicle such as a car, van, truck, bus, etc. In suchimplementations, the prime mover 104 may include one or more electricmotors and/or an internal combustion engine (among others). The energysource may include, for example, a fuel system (e.g., providinggasoline, diesel, hydrogen, etc.), a battery system, solar panels orother renewable energy source, and/or a fuel cell system. The drivetrain108 can include wheels and/or tires along with a transmission and/or anyother mechanical drive components to convert the output of the primemover 104 into vehicular motion, as well as one or more brakesconfigured to controllably stop or slow the vehicle 100 and direction orsteering components suitable for controlling the trajectory of thevehicle 100 (e.g., a rack and pinion steering linkage enabling one ormore wheels of the vehicle 100 to pivot about a generally vertical axisto vary an angle of the rotational planes of the wheels relative to thelongitudinal axis of the vehicle). In some implementations, combinationsof powertrains and energy sources may be used (e.g., in the case ofelectric/gas hybrid vehicles), and in some instances multiple electricmotors (e.g., dedicated to individual wheels or axles) may be used as aprime mover.

The direction control 112 may include one or more actuators and/orsensors for controlling and receiving feedback from the direction orsteering components to enable the vehicle 100 to follow a desiredtrajectory. The powertrain control 114 may be configured to control theoutput of the powertrain 102, e.g., to control the output power of theprime mover 104, to control a gear of a transmission in the drivetrain108, etc., thereby controlling a speed and/or direction of the vehicle100. The brake control 116 may be configured to control one or morebrakes that slow or stop vehicle 100, e.g., disk or drum brakes coupledto the wheels of the vehicle.

Other vehicle types, including but not limited to off-road vehicles,all-terrain or tracked vehicles, construction equipment etc., willnecessarily utilize different powertrains, drivetrains, energy sources,direction controls, powertrain controls and brake controls. Moreover, insome implementations, some of the components can be combined, e.g.,where directional control of a vehicle is primarily handled by varyingan output of one or more prime movers. Therefore, implementationsdisclosed herein are not limited to the particular application of theherein-described techniques in an autonomous wheeled land vehicle.

Various levels of autonomous control over the vehicle 100 can beimplemented in a vehicle control system 120, which may include one ormore processors 122 and one or more memories 124, with each processor122 configured to execute program code instructions 126 stored in amemory 124. The processors(s) can include, for example, graphicsprocessing unit(s) (“GPU(s)”)) and/or central processing unit(s)(“CPU(s)”).

Sensors 130 may include various sensors suitable for collectinginformation from a vehicle's surrounding environment for use incontrolling the operation of the vehicle. For example, sensors 130 caninclude radar sensor 134, LIDAR (Light Detection and Ranging) sensor136, a 3D positioning sensors 138, e.g., any of an accelerometer, agyroscope, a magnetometer, or a satellite navigation system such as GPS(Global Positioning System), GLONASS (Globalnaya NavigazionnayaSputnikovaya Sistema, or Global Navigation Satellite System), BeiDouNavigation Satellite System (BDS), Galileo, Compass, etc. The 3Dpositioning sensors 138 can be used to determine the location of thevehicle on the Earth using satellite signals. The sensors 130 caninclude a camera 140 and/or an IMU (inertial measurement unit) 142. Thecamera 140 can be a monographic or stereographic camera and can recordstill and/or video images. The IMU 142 can include multiple gyroscopesand accelerometers capable of detecting linear and rotational motion ofthe vehicle in three directions. One or more encoders (not illustrated),such as wheel encoders may be used to monitor the rotation of one ormore wheels of vehicle 100. Each sensor 130 can output sensor data atvarious data rates, which may be different than the data rates of othersensors 130.

The outputs of sensors 130 may be provided to a set of controlsubsystems 150, including, a localization subsystem 152, a planningsubsystem 156, a perception subsystem 154, and a control subsystem 158.The localization subsystem 152 can perform functions such as preciselydetermining the location and orientation (also sometimes referred to as“pose”) of the vehicle 100 within its surrounding environment, andgenerally within some frame of reference. The location of an autonomousvehicle can be compared with the location of an additional vehicle inthe same environment as part of generating labeled autonomous vehicledata. The perception subsystem 154 can perform functions such asdetecting, tracking, determining, and/or identifying objects within theenvironment surrounding vehicle 100. A machine learning model inaccordance with some implementations can be utilized in trackingobjects. The planning subsystem 156 can perform functions such asplanning a trajectory for vehicle 100 over some timeframe given adesired destination as well as the static and moving objects within theenvironment. A machine learning model in accordance with someimplementations can be utilized in planning a vehicle trajectory. Thecontrol subsystem 158 can perform functions such as generating suitablecontrol signals for controlling the various controls in the vehiclecontrol system 120 in order to implement the planned trajectory of thevehicle 100. A machine learning model can be utilized to generate one ormore signals to control an autonomous vehicle to implement the plannedtrajectory.

It will be appreciated that the collection of components illustrated inFIG. 1 for the vehicle control system 120 is merely exemplary in nature.Individual sensors may be omitted in some implementations. Additionallyor alternatively, in some implementations, multiple sensors of typesillustrated in FIG. 1 may be used for redundancy and/or to coverdifferent regions around a vehicle, and other types of sensors may beused. Likewise, different types and/or combinations of controlsubsystems may be used in other implementations. Further, whilesubsystems 152-158 are illustrated as being separate from processor 122and memory 124, it will be appreciated that in some implementations,some or all of the functionality of a subsystem 152-158 may beimplemented with program code instructions 126 resident in one or morememories 124 and executed by one or more processors 122, and that thesesubsystems 152-158 may in some instances be implemented using the sameprocessor(s) and/or memory. Subsystems may be implemented at least inpart using various dedicated circuit logic, various processors, variousfield programmable gate arrays (“FPGA”), various application-specificintegrated circuits (“ASIC”), various real time controllers, and thelike, as noted above, multiple subsystems may utilize circuitry,processors, sensors, and/or other components. Further, the variouscomponents in the vehicle control system 120 may be networked in variousmanners.

In some implementations, the vehicle 100 may also include a secondaryvehicle control system (not illustrated), which may be used as aredundant or backup control system for the vehicle 100. In someimplementations, the secondary vehicle control system may be capable offully operating the autonomous vehicle 100 in the event of an adverseevent in the vehicle control system 120, while in other implementations,the secondary vehicle control system may only have limitedfunctionality, e.g., to perform a controlled stop of the vehicle 100 inresponse to an adverse event detected in the primary vehicle controlsystem 120. In still other implementations, the secondary vehiclecontrol system may be omitted.

In general, an innumerable number of different architectures, includingvarious combinations of software, hardware, circuit logic, sensors,networks, etc. may be used to implement the various componentsillustrated in FIG. 1. Each processor may be implemented, for example,as a microprocessor and each memory may represent the random accessmemory (“RAM”) devices comprising a main storage, as well as anysupplemental levels of memory, e.g., cache memories, non-volatile orbackup memories (e.g., programmable or flash memories), read-onlymemories, etc. In addition, each memory may be considered to includememory storage physically located elsewhere in the vehicle 100, e.g.,any cache memory in a processor, as well as any storage capacity used asa virtual memory, e.g., as stored on a mass storage device or anothercomputer controller. One or more processors illustrated in FIG. 1, orentirely separate processors, may be used to implement additionalfunctionality in the vehicle 100 outside of the purposes of autonomouscontrol, e.g., to control entertainment systems, to operate doors,lights, convenience features, etc.

In addition, for additional storage, the vehicle 100 may include one ormore mass storage devices, e.g., a removable disk drive, a hard diskdrive, a direct access storage device (“DASD”), an optical drive (e.g.,a CD drive, a DVD drive, etc.), a solid state storage drive (“SSD”),network attached storage, a storage area network, and/or a tape drive,among others.

Furthermore, the vehicle 100 may include a user interface 164 to enablevehicle 100 to receive a number of inputs from and generate outputs fora user or operator, e.g., one or more displays, touchscreens, voiceand/or gesture interfaces, buttons and other tactile controls, etc.Otherwise, user input may be received via another computer or electronicdevice, e.g., via an app on a mobile device or via a web interface.

Moreover, the vehicle 100 may include one or more network interfaces,e.g., network interface 162, suitable for communicating with one or morenetworks 170 (e.g., a Local Area Network (“LAN”), a wide area network(“WAN”), a wireless network, and/or the Internet, among others) topermit the communication of information with other computers andelectronic device, including, for example, a central service, such as acloud service, from which the vehicle 100 receives environmental andother data for use in autonomous control thereof. Data collected by theone or more sensors 130 can be uploaded to a computing system 172 viathe network 170 for additional processing. In some implementations, atime stamp can be added to each instance of vehicle data prior touploading.

Each processor illustrated in FIG. 1, as well as various additionalcontrollers and subsystems disclosed herein, generally operates underthe control of an operating system and executes or otherwise relies uponvarious computer software applications, components, programs, objects,modules, data structures, etc., as will be described in greater detailbelow. Moreover, various applications, components, programs, objects,modules, etc. may also execute on one or more processors in anothercomputer coupled to vehicle 100 via network 170, e.g., in a distributed,cloud-based, or client-server computing environment, whereby theprocessing required to implement the functions of a computer program maybe allocated to multiple computers and/or services over a network.

In general, the routines executed to implement the variousimplementations described herein, whether implemented as part of anoperating system or a specific application, component, program, object,module or sequence of instructions, or even a subset thereof, will bereferred to herein as “program code”. Program code can include one ormore instructions that are resident at various times in various memoryand storage devices, and that, when read and executed by one or moreprocessors, perform the steps necessary to execute steps or elementsembodying the various aspects of the present disclosure. Moreover, whileimplementations have and hereinafter will be described in the context offully functioning computers and systems, it will be appreciated that thevarious implementations described herein are capable of beingdistributed as a program product in a variety of forms, and thatimplementations can be implemented regardless of the particular type ofcomputer readable media used to actually carry out the distribution.

Examples of computer readable media include tangible, non-transitorymedia such as volatile and non-volatile memory devices, floppy and otherremovable disks, solid state drives, hard disk drives, magnetic tape,and optical disks (e.g., CD-ROMs, DVDs, etc.) among others.

In addition, various program code described hereinafter may beidentified based upon the application within which it is implemented ina specific implementation. However, it should be appreciated that anyparticular program nomenclature that follows is used merely forconvenience, and thus the present disclosure should not be limited touse solely in any specific application identified and/or implied by suchnomenclature. Furthermore, given the typically endless number of mannersin which computer programs may be organized into routines, procedures,methods, modules, objects, and the like, as well as the various mannersin which program functionality may be allocated among various softwarelayers that are resident within a typical computer (e.g., operatingsystems, libraries, API's, applications, applets, etc.), it should beappreciated that the present disclosure is not limited to the specificorganization and allocation of program functionality described herein.

The environment illustrated in FIG. 1 is not intended to limitimplementations disclosed herein. Indeed, other alternative hardwareand/or software environments may be used without departing from thescope of implementations disclosed herein.

2. Coherent Signal Combining with Multiple-Outputs

FIG. 2A is a block diagram depicting an example quasi-CW LIDAR systemfor operating of a vehicle, according to some implementations. Thequasi-CW LIDAR system 200 a includes a laser source 202 for providing alight signal (sometimes referred to as, “beam”).

The quasi-CW LIDAR system 200 a includes a modulator 204 for modulatingthe light signal and a coherent signal generator 206 (sometimes referredto as, “signal processing system”) for coherent signal generating (e.g.,combining, merging, adding, mixing, etc.) with multiple-outputs forquasi-CW LIDAR operation. That is, the modulator 204 receives the lightsignal from the laser source 202, modulates a phase and/or a frequencyof the light signal using Continuous Wave (CW) modulation or quasi-CWmodulation, and provides the modulated signal to one or more inputchannels of the coherent signal generator 206.

The coherent signal generator 206 combines the received modulatedsignals to generate a continuous wave signal across the plurality ofoutputs (e.g., output channels 312 a-312 d in FIG. 3) of the coherentsignal generator 206, and provide the continuous wave signal to ascanner 208 (e.g., an oscillatory scanner, a unidirectional scanner, aRisley prism, etc.). In some implementations, the coherent signalgenerator 206 generates the continuous wave signal by operating aplurality of sub-amplifiers (e.g., SOAs 308 a-d in FIG. 3) on differentduty cycles.

Based on the received continuous signal, the scanner 208 generates oneor more scanning signals to drive one or more optical elements for theoptical detection of an object 210.

As shown in FIG. 2A, the modulator 204 may be separate from the coherentsignal generator 206.

Any of the components (e.g., laser source 202, modulator 204, coherentsignal generator 206, and scanner 208) of the quasi-CW LIDAR system 200a may be included in one or more semiconductor packages. For example,the laser 202 may be in a first semiconductor package, the coherentsignal generator 204 may be in a second semiconductor package, and thescanner 206 may be in a third semiconductor package. As another example,a semiconductor package may include the laser 202, the modulator 204,the coherent signal generator 206, and the scanner 208.

FIG. 2B is a block diagram depicting an example quasi-CW LIDAR systemfor operating of a vehicle, according to some implementations. Thequasi-CW LIDAR system 200 b includes the laser source 202, the coherentsignal generator 206, and the scanner 208 for the optical detection ofthe object 210. The coherent signal generator 206 in FIG. 2B includesthe features and/or functionality of the modulator 204 in FIG. 2A.

Any of the components (e.g., laser source 202, coherent signal generator206, and scanner 208) of the quasi-CW LIDAR system 200 b may be includedin one or more semiconductor packages.

FIG. 3 is a block diagram depicting an example environment of a coherentsignal generator architecture (e.g., coherent signal generator 206 inFIG. 2A, coherent signal generator 206 in FIG. 2B) for coherent signalcombining with multiple-outputs for quasi-CW LIDAR operation, accordingto some implementations. The environment 300 includes a laser source 202for providing a light signal (sometimes referred to as, “beam”). Theenvironment 300 includes a modulator 204 for modulating the phase and/orthe frequency of the light signal using Continuous Wave (CW) modulationor quasi-CW modulation to generate a modulated signal.

The environment 300 includes a phase shifter network 306 for adjustingthe phase of the modulated signal and providing the modulated signal toan amplifier 308. The phase shifter 306 contains a phase shifter 306 a,a phase shifter 306 b, a phase shifter 306 c, and a phase shifter 306 d;collectively referred to as, “phase shifters 306 a-d”.

The amplifier 308 includes sub-amplifiers, such as an SOA 308 a, an SOA308 b, an SOA 308 c, and an SOA 308 d; collectively referred to as,“SOAs 308 a-d”. Each of the sub-amplifiers produces an amplified signal.

The environment 300 includes a beam splitter network 310 (sometimesreferred to as, “splitter 310”) that produces output waveforms bycombining some or all of the amplified signals based on constructive anddestructive interference principles. The beam splitter network 310includes a beam splitter 310 a (shown in FIG. 3 as, “50/50 310 a”), abeam splitter 310 b (shown in FIG. 3 as, “50/50 310 b”), a beam splitter310 c (shown in FIG. 3 as, “50/50 310 c”), and a beam splitter 310 d(shown in FIG. 3 as, “50/50 310 d”); collectively referred to as, “beamsplitters 310 a-d”.

The environment 300 includes output channel 312 a, output channel 312 b,output channel 312 c, and output channel 312 d; collectively referred toas, “output channels 312 a-d”. Although FIG. 3 shows only a selectnumber of components (e.g., laser source 202, modulator 204, phaseshifters 306 a-d, SOAs 308 a-d, and beam splitters 310 a-d) and outputchannels 312 a-d; it will be appreciated by those skilled in the artthat the environment 300 may include any number of components and/oroutput channels (in any combination) that are interconnected in anyarrangement to facilitate coherent signal combining for quasi-CW LIDARoperation. For example, an 8-channel coherent signal generatorarchitecture (e.g., as shown in FIG. 8) would include 8 phase shifters,8 SOAs, 8 output channels, and 13 splitters. As another example, a16-channel coherent signal generator would include 16 phase-shifters, 16SOAs, 16 output channels, and 26 splitters.

The laser source 202 couples to an input terminal of the modulator 204,whose output couples to an input terminal of the phase shifter 306 a, aninput terminal of the phase shifter 306 b, an input terminal of thephase shifter 306 c, and an input terminal of the phase shifter 306 d.

An output terminal of the phase shifter 306 a couples to an inputterminal of the SOA 308 a, whose output terminal couples to a firstinput terminal of the beam splitter 310 b. An output terminal of thephase shifter 306 b couples to an input terminal of the SOA 308 b, whoseoutput terminal couples to a first input terminal of the beam splitter310 a. An output terminal of the phase shifter 306 c couples to an inputterminal of the SOA 308 c, whose output terminal couples to a secondinput terminal of the beam splitter 310 a. An output terminal of thephase shifter 306 d couples to an input terminal of the SOA 308 d, whoseoutput terminal couples to a second input terminal of the beam splitter310 b.

A first output terminal of the beam splitter 310 a couples to a firstinput terminal of the beam splitter 310 c, whose first output terminalcouples to an output channel 312 a (shown in FIG. 3 as, “output 312 a”)and second output terminal couples to an output channel 312 b (shown inFIG. 3 as, “output 312 b”).

A second output terminal of the beam splitter 310 a couples to a secondinput terminal of the beam splitter 310 d, whose first output terminalcouples to an output channel 312 c (shown in FIG. 3 as, “output 312 c”)and second output terminal couples to an output channel 312 d (shown inFIG. 3 as, “output 312 d”).

A first output terminal of the beam splitter 310 b couples to a secondinput terminal of the beam splitter 310 c and a second output terminalof the beam splitter 310 b couples to a first input terminal of the beamsplitter 310 d.

A semiconductor packaging (not shown in FIG. 3), in someimplementations, may include some or all of the components (e.g., lasersource 202, modulator 204, phase shifters 306 a-d, SOAs 308 a-d, andbeam splitters 310 a-d) of environment 300. For example, a firstsemiconductor packaging may include the components of the modulator 204;and a second semiconductor packaging may include the components of thephase shifter 306 (e.g., phase shifters 306 a-d), the components of theamplifier 308 (e.g., SOAs 308 a-d), and/or the components of the beamsplitter network 310 (e.g., beam splitters 310 a-d). In thisarrangement, one or more outputs of the first semiconductor packagingmay be coupled to the one or more inputs of the second semiconductorpackaging.

As another example, a semiconductor packaging may include the componentsof the modulator 204, the components of the phase shifter 306 (e.g.,phase shifters 306 a-d), the components of the amplifier 308 (e.g., SOAs308 a-d), and/or the components of the beam splitter network 310 (e.g.,beam splitters 310 a-d). In this arrangement, the laser 202 may becoupled to the one or more inputs of the semiconductor packaging.

The output channels 312 a-312 d, in some implementations, may correspondto outputs on a semiconductor packaging.

Still referring to FIG. 3, by operating the sub-amplifiers (e.g., SOAs308 a-d) on different duty cycles, the amplifier 308 and the beamsplitter network 310 may produce a continuous output waveform (e.g.,output waveforms 402 a-d in FIG. 4) across the output channels 312 a-312d of the coherent signal generator. That is, the continuous wave powerfrom each SOA 308 a-d may be summed (based on the constructive anddestructive interference principles) coherently in the beam splitternetwork 310 to ideally increase the output power to a single outputchannel at a time by N where N is the number of sub-amplifiers. Thisincreased output power may be directed (e.g., routed, focused, etc.) atdifferent times to different outputs providing switching to increase theeffective number of available channels. The difficulty comes in thecontrol of the phases in the beam splitter network 310 which depend onthe optical path lengths of waveguides. In some implementations, some orall of the paths between the beam splitters 310 a-310 d may be matched.In some implementations, with good design and/or process control thenumber of phase shifters (e.g., phase shifters 306 a-d) needed forcontrol of the output may be reduced.

FIG. 4 is a time-based graph 400 depicting quasi-CW waveforms asmeasured at the output channels 312 a-312 d of the coherent signalgenerator in FIG. 3, in accordance with an illustrative implementation.The time-base graph includes output waveform 402 a, output waveform 402b, output waveform 402 c, and output waveform 402 b; each of which arequasi-CW waveforms resulting from operating the components of thecoherent signal generator (e.g., laser source 202, modulator 204, phaseshifters 306 a-d, SOAs 308 a-d, and beam splitters 310 a-d) under a setof operating conditions.

For example, referring to FIG. 3, the laser 202 drives the modulatorwith a 400 mW continuous wave (e.g., up to 95% duty cycle). Themodulator 204 modulates a phase and/or a frequency of the received lightsignal using quasi-CW modulation to produce a modulated light signal andsends the modulated light signal to each of the input terminals of thephase shifters 306 a-d. Each of the phase shifters 306 a-d, ascontrolled by a processor (not shown in FIG. 3), shifts (e.g., adjusts,modifies, etc.) the phase of the modulated signal that it receives toproduce a shifted modulated signal and sends the shifted modulatedsignal to the amplifier 308. The amplifier 308 amplifies each of theshifted modulated signals (four copies) that it receives from the phaseshifter 306, to produce a first amplified signal that measures 100 mW attap 309 a, a second amplified signal that measures 100 mW at tap 309 b,a third amplified signal that measures 100 mW at tap 309 c, and a fourthamplified signal that measures 100 mW at tap 309 d. The amplifier 308sends the amplified signals (e.g., the first amplified signal, thesecond amplified signal, the third amplified signal, and the fourthamplified signal) to the beam splitter network 310, which producesoutput waveform 402 a at output channel 312 a, output waveform 402 b atoutput channel 312 b, output waveform 402 c at output channel 312 c, andoutput waveform 402 d at output channel 312 d.

The beam splitter network 310 produces each of the output waveforms 412a-412 d by combining some or all of the amplified signals based onconstructive and destructive interference principles.

In constructive interference, the beam splitter network 310 combines twowaveforms to produce a resultant waveform having an amplitude that ishigher than each of the two waveforms. For example, if the beam splitternetwork 310 combines two waveforms that have the same amplitude, thenthe resultant waveform would have a maximum amplitude that is twice theamplitude of the two waveforms. The region where the amplitude isbetween the original amplitude and the maximum amplitude is referred asthe constructive interference. The constructive interference occurs whenthe waveforms are in-phase with each other.

In destructive interference, the beam splitter network 310 combines twowaveforms to produce a resultant waveform having an amplitude that islower than each of the two waveforms. For example, if the beam splitternetwork 310 combines two waveforms that have the same amplitude, thenthe resultant waveform would have a minimum amplitude that is zero. Inthis case, the resultant waveform would completely disappears at someplaces. The region between the original amplitude and the minimumamplitude is known as the region of destructive interference.Destructive interference occurs when the waveforms are out-of-phase witheach other.

FIG. 5 is a time-based graph depicting the summation of the outputpowers from the SOAs 308 a-308 d of the coherent signal generator inFIG. 3, in accordance with an illustrative implementation. The time-basegraph 500 depicts the relationship between the output waveform 402 a atthe output channel 312 a (shown in FIG. 5 as, “Ch1”), the outputwaveform 402 b at the output channel 312 b (shown in FIG. 5 as, “Ch2”),the output waveform 402 c at the output channel 312 c (shown in FIG. 5as, “Ch3”), and the output waveform 402 d at the output channel 312 d(shown in FIG. 5 as, “Ch4”).

With the beam splitter network 310 including beam splitters 310 a-d(e.g., 50:50 2×2 splitters), it is straightforward to determine thephases of the light after the SOAs 308 a-d that are needed to direct thelight into a particular output channel 312 a-312 d. Each beam splitter310 a-d may be parameterized as a 2×2 scattering matrix according toEquation (1):

$\begin{matrix}{{{\overset{\rightarrow}{E}}_{out} = {M{\overset{\rightarrow}{E}}_{in}}},{{{where}\mspace{14mu} M} = \begin{bmatrix}{i/\sqrt{2}} & 0 \\0 & {1/\sqrt{2}}\end{bmatrix}}} & (1)\end{matrix}$

The full network may be scaled-up. For example, the coherent signalgenerator (e.g., a 4×4 network) in FIG. 3 may be parameterized as twolayers of 4×4 scattering matrices each of which are made up of 2×2sub-matrices describing the 2×2 splitters in each layer. The finalmatrix for the 4×4 network shown in FIG. 3 may be based on Equation (2):

$\begin{matrix}{M = {1/{2\begin{bmatrix}{- 1} & i & 1 & i \\i & {- 1} & i & 1 \\1 & i & {- 1} & i \\i & 1 & i & {- 1}\end{bmatrix}}}} & (2)\end{matrix}$

This scattering matrix may then be inverted to find the phases of theinput fields that result in all the power being directed to a singleoutput channel 312 a-d, according to Equation (3):E _(in) ^(→) =M ⁻¹ E _(out) ^(→)  (3)

If E_(out) ^(→)=[2,0,0,0]^(T) is desired representing 4 times the lightof one individual channel being provided out of the upper most outputchannel (e.g., output channel 112 a). The phases, in someimplementations, on the input channels are φ=[0, π/2, π/2]^(T) or [0deg., 90 deg., 180 deg., 90 deg.] as illustrated in FIG. 6.

FIG. 6 is a block diagram depicting the example environment of thecoherent signal generator architecture in FIG. 3 when configured todirect all the light onto an output channel, according to someimplementations. The environment 600 shows the amplitude and phases fordirecting all of the light onto the output channel 312 a, assuming allthe paths from input into the beam splitter network 310 to all theoutput channels 312 a-d have the same length. The phases are relative,so any rotation of all the phases by the same amount lead to all of thelight remaining in the same output channel.

As shown in FIG. 6, the phase shifter 306 a is configured to 0 degrees,the phase shifter 306 b is configured to 90 degrees, the phase shifter306 c is configured to 180 degrees, the phase shifter 306 d isconfigured to 90 degrees, the amplified signal at tap 309 a is 100 mW,the amplified signal at tap 309 b is 100 mW, the amplified signal at tap309 c is 100 mW, and the amplified signal at tap 309 d is 100 mW. Underthese conditions, the coherent signal generator produces a 400 mWwaveform (100 mW+100 mW+100 mW+100 mW=400 mW) at the output channel 312a and 0 mW at output channels 312 b, 312 c, 312 d.

FIG. 7 is a block diagram depicting the example environment of thecoherent signal generator architecture in FIG. 3 when configured todirect all the light onto an output channel, according to someimplementations. The environment 700 shows the amplitude and phases fordirecting all of the light onto the output channel 312 b, assuming allthe paths from input into the beam splitter network 310 to all theoutput channels 312 a-d have the same length. The phases are relative,so any rotation of all the phases by the same amount lead to all of thelight remaining in the same output channel.

As shown in FIG. 7, the phase shifter 306 a is configured to 90 degrees,the phase shifter 306 b is configured to 0 degrees, the phase shifter306 c is configured to 90 degrees, the phase shifter 306 d is configuredto 180 degrees, the amplified signal at tap 309 a is 100 mW, theamplified signal at tap 309 b is 100 mW, the amplified signal at tap 309c is 100 mW, and the amplified signal at tap 309 d is 100 mW. Underthese conditions, the coherent signal generator produces a 400 mWwaveform (100 mW+100 mW+100 mW+100 mW=400 mW) at the output channel 312b and 0 mW at output channels 112 a, 112 c, 112 d.

FIG. 8 is a block diagram depicting the example environment of thecoherent signal generator architecture in FIG. 3 when configured todirect all the light onto an output channel, according to someimplementations. The environment 800 shows the amplitude and phases fordirecting all of the light onto the output channel 312 c, assuming allthe paths from input into the beam splitter network 310 to all theoutput channels 312 a-d have the same length. The phases are relative,so any rotation of all the phases by the same amount lead to all of thelight remaining in the same output channel.

As shown in FIG. 8, the phase shifter 306 a is configured to 180degrees, the phase shifter 306 b is configured to 90 degrees, the phaseshifter 306 c is configured to 0 degrees, the phase shifter 306 d isconfigured to 90 degrees, the amplified signal at tap 309 a is 100 mW,the amplified signal at tap 309 b is 100 mW, the amplified signal at tap309 c is 100 mW, and the amplified signal at tap 309 d is 100 mW. Underthese conditions, the coherent signal generator produces a 400 mWwaveform (100 mW+100 mW+100 mW+100 mW=400 mW) at the output channel 312c and 0 mW at output channels 312 a, 312 b, 312 d.

FIG. 9 is a block diagram depicting the example environment of thecoherent signal generator architecture in FIG. 3 when configured todirect all the light onto an output channel, according to someimplementations. The environment 900 shows the amplitude and phases fordirecting all of the light onto the output channel 312 d, assuming allthe paths from input into the beam splitter network 310 to all theoutput channels 312 a-d have the same length. The phases are relative,so any rotation of all the phases by the same amount lead to all of thelight remaining in the same output channel.

As shown in FIG. 9, the phase shifter 306 a is configured to 90 degrees,the phase shifter 306 b is configured to 180 degrees, the phase shifter306 c is configured to 90 degrees, the phase shifter 306 d is configuredto 0 degrees, the amplified signal at tap 309 a is 100 mW, the amplifiedsignal at tap 309 b is 100 mW, the amplified signal at tap 309 c is 100mW, and the amplified signal at tap 309 d is 100 mW. Under theseconditions, the coherent signal generator produces a 400 mW waveform(100 mW+100 mW+100 mW+100 mW=400 mW) at the output channel 312 d and 0mW at output channels 312 a, 312 b, 312 c.

FIG. 10 is a block diagram depicting an example environment of acoherent signal generator architecture for coherent signal combiningwith multiple-outputs for quasi-CW LIDAR operation, according to someimplementations. The environment 1000 includes a laser source 202 forproviding a light signal. The environment 1000 includes a modulator 204for modulating a phase and/or a frequency of the light signal usingContinuous Wave (CW) modulation or quasi-CW modulation to generate amodulated signal.

The environment 1000 includes a phase shifter network for adjusting thephase of the modulated signal and providing the modulated signal to anamplifier. The phase shifter network contains a phase shifter 1006 a, aphase shifter 1006 b, a phase shifter 1006 c, a phase shifter 1006 d, aphase shifter 1006 e, a phase shifter 1006 f, a phase shifter 1006 g,and a phase shifter 1006 h; collectively referred to as, “phase shifters1006 a-h”.

The amplifier includes sub-amplifiers, such as an SOA 1008 a, an SOA1008 b, an SOA 1008 c, an SOA 1008 d, an SOA 1008 e, an SOA 1008 f, anSOA 1008 g, and an SOA 1008 h; collectively referred to as, “SOAs 1008a-h”. Each of the sub-amplifiers produces an amplified signal.

The environment 1000 includes a beam splitter network 1010 that producesoutput waveforms by combining some or all of the amplified signals basedon constructive and destructive interference principles. The beamsplitter network 1010 includes a beam splitter 1010 a (shown in FIG. 10as, “50/50 1010 a”), a beam splitter 1010 b (shown in FIG. 10 as, “50/501010 b”), a beam splitter 1010 c (shown in FIG. 10 as, “50/50 1010 c”),a beam splitter 1010 d (shown in FIG. 10 as, “50/50 1010 d”), a beamsplitter 1010 e (shown in FIG. 10 as, “50/50 1010 e”), a beam splitter1010 f (shown in FIG. 10 as, “50/50 1010 f”), a beam splitter 1010 g(shown in FIG. 10 as, “50/50 1010 g”), a beam splitter 1010 h (shown inFIG. 10 as, “50/50 1010 h”), a beam splitter 1010 i (shown in FIG. 10as, “50/50 1010 i”), a beam splitter 1010 j (shown in FIG. 10 as, “50/501010 j”), a beam splitter 1010 k (shown in FIG. 10 as, “50/50 1010 k”),a beam splitter 1010 l (shown in FIG. 10 as, “50/50 1010 l”), and a beamsplitter 1010 m (shown in FIG. 10 as, “50/50 1010 m”); collectivelyreferred to as, “beam splitters 1010 a-m”.

The environment 1000 includes output channel 1012 a, output channel 1012b, output channel 1012 c, output channel 1012 d, output channel 1012 e,output channel 1012 f, output channel 1012 g, and output channel 1012 h;collectively referred to as, “output channels 1012 a-h”. Although FIG.10 shows only a select number of components (e.g., laser source 202,modulator 204, phase shifters 1006 a-h, SOAs 1008 a-h, and beamsplitters 1010 a-m) and output channels 1012 a-h; it will be appreciatedby those skilled in the art that the environment 1000 may include anynumber of components and/or output channels (in any combination) thatare interconnected in any arrangement to facilitate coherent signalcombining for quasi-CW LIDAR operation.

The previous description is provided to enable any person skilled in theart to practice the various aspects described herein. Variousmodifications to these aspects will be readily apparent to those skilledin the art, and the generic principles defined herein may be applied toother aspects. Thus, the claims are not intended to be limited to theaspects shown herein, but is to be accorded the full scope consistentwith the language claims, wherein reference to an element in thesingular is not intended to mean “one and only one” unless specificallyso stated, but rather “one or more.” Unless specifically statedotherwise, the term “some” refers to one or more. All structural andfunctional equivalents to the elements of the various aspects describedthroughout the previous description that are known or later come to beknown to those of ordinary skill in the art are expressly incorporatedherein by reference and are intended to be encompassed by the claims.Moreover, nothing disclosed herein is intended to be dedicated to thepublic regardless of whether such disclosure is explicitly recited inthe claims. No claim element is to be construed as a means plus functionunless the element is expressly recited using the phrase “means for.”

It is understood that the specific order or hierarchy of blocks in theprocesses disclosed is an example of illustrative approaches. Based upondesign preferences, it is understood that the specific order orhierarchy of blocks in the processes may be rearranged while remainingwithin the scope of the previous description. The accompanying methodclaims present elements of the various blocks in a sample order, and arenot meant to be limited to the specific order or hierarchy presented.

The previous description of the disclosed implementations is provided toenable any person skilled in the art to make or use the disclosedsubject matter. Various modifications to these implementations will bereadily apparent to those skilled in the art, and the generic principlesdefined herein may be applied to other implementations without departingfrom the spirit or scope of the previous description. Thus, the previousdescription is not intended to be limited to the implementations shownherein but is to be accorded the widest scope consistent with theprinciples and novel features disclosed herein.

The various examples illustrated and described are provided merely asexamples to illustrate various features of the claims. However, featuresshown and described with respect to any given example are notnecessarily limited to the associated example and may be used orcombined with other examples that are shown and described. Further, theclaims are not intended to be limited by any one example.

The foregoing method descriptions and the process flow diagrams areprovided merely as illustrative examples and are not intended to requireor imply that the blocks of various examples must be performed in theorder presented. As will be appreciated by one of skill in the art theorder of blocks in the foregoing examples may be performed in any order.Words such as “thereafter,” “then,” “next,” etc. are not intended tolimit the order of the blocks; these words are simply used to guide thereader through the description of the methods. Further, any reference toclaim elements in the singular, for example, using the articles “a,”“an” or “the” is not to be construed as limiting the element to thesingular.

The various illustrative logical blocks, modules, circuits, andalgorithm blocks described in connection with the examples disclosedherein may be implemented as electronic hardware, computer software, orcombinations of both. To clearly illustrate this interchangeability ofhardware and software, various illustrative components, blocks, modules,circuits, and blocks have been described above generally in terms oftheir functionality. Whether such functionality is implemented ashardware or software depends upon the particular application and designconstraints imposed on the overall system. Skilled artisans mayimplement the described functionality in varying ways for eachparticular application, but such implementation decisions should not beinterpreted as causing a departure from the scope of the presentdisclosure.

The hardware used to implement the various illustrative logics, logicalblocks, modules, and circuits described in connection with the examplesdisclosed herein may be implemented or performed with a general purposeprocessor, a DSP, an ASIC, an FPGA or other programmable logic device,discrete gate or transistor logic, discrete hardware components, or anycombination thereof designed to perform the functions described herein.A general-purpose processor may be a microprocessor, but, in thealternative, the processor may be any conventional processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices, e.g., a combinationof a DSP and a microprocessor, a plurality of microprocessors, one ormore microprocessors in conjunction with a DSP core, or any other suchconfiguration. Alternatively, some blocks or methods may be performed bycircuitry that is specific to a given function.

In some exemplary examples, the functions described may be implementedin hardware, software, firmware, or any combination thereof. Ifimplemented in software, the functions may be stored as one or moreinstructions or code on a non-transitory computer-readable storagemedium or non-transitory processor-readable storage medium. The blocksof a method or algorithm disclosed herein may be embodied in aprocessor-executable software module which may reside on anon-transitory computer-readable or processor-readable storage medium.Non-transitory computer-readable or processor-readable storage media maybe any storage media that may be accessed by a computer or a processor.By way of example but not limitation, such non-transitorycomputer-readable or processor-readable storage media may include RAM,ROM, EEPROM, FLASH memory, CD-ROM or other optical disk storage,magnetic disk storage or other magnetic storage devices, or any othermedium that may be used to store desired program code in the form ofinstructions or data structures and that may be accessed by a computer.Disk and disc, as used herein, includes compact disc (CD), laser disc,optical disc, digital versatile disc (DVD), floppy disk, and blu-raydisc where disks usually reproduce data magnetically, while discsreproduce data optically with lasers. Combinations of the above are alsoincluded within the scope of non-transitory computer-readable andprocessor-readable media. Additionally, the operations of a method oralgorithm may reside as one or any combination or set of codes and/orinstructions on a non-transitory processor-readable storage mediumand/or computer-readable storage medium, which may be incorporated intoa computer program product.

The preceding description of the disclosed examples is provided toenable any person skilled in the art to make or use the presentdisclosure. Various modifications to these examples will be readilyapparent to those skilled in the art, and the generic principles definedherein may be applied to some examples without departing from the spiritor scope of the disclosure. Thus, the present disclosure is not intendedto be limited to the examples shown herein but is to be accorded thewidest scope consistent with the following claims and the principles andnovel features disclosed herein.

Notwithstanding that the numerical ranges and parameters setting forththe broad scope are approximations, the numerical values set forth inspecific non-limiting examples are reported as precisely as possible.Any numerical value, however, inherently contains certain errorsnecessarily resulting from the standard deviation found in theirrespective testing measurements at the time of this writing.Furthermore, unless otherwise clear from the context, a numerical valuepresented herein has an implied precision given by the least significantdigit. Thus a value 1.1 implies a value from 1.05 to 1.15. The term“about” is used to indicate a broader range centered on the given value,and unless otherwise clear from the context implies a broader rangearound the least significant digit, such as “about 1.1” implies a rangefrom 1.0 to 1.2. If the least significant digit is unclear, then theterm “about” implies a factor of two, e.g., “about X” implies a value inthe range from 0.5X to 2X, for example, about 100 implies a value in arange from 50 to 200. Moreover, all ranges disclosed herein are to beunderstood to encompass any and all sub-ranges subsumed therein. Forexample, a range of “less than 10” for a positive only parameter caninclude any and all sub-ranges between (and including) the minimum valueof zero and the maximum value of 10, that is, any and all sub-rangeshaving a minimum value of equal to or greater than zero and a maximumvalue of equal to or less than 10 (e.g., 1 to 4).

Some implementations of the present disclosure are described below inthe context of one or more hi-res Doppler LIDAR systems that are mountedonto an area (e.g., front, back, side, top, and/or bottom) of a personalautomobile; but, implementations are not limited to this context. Inother implementations, one or multiple systems of the same type or otherhigh resolution LIDAR, with or without Doppler components, withoverlapping or non-overlapping fields of view or one or more suchsystems mounted on smaller or larger land, sea or air vehicles, pilotedor autonomous, are employed. In other implementations, the scanninghi-res LIDAR is mounted at temporary or permanent fixed positions onland or sea.

What is claimed is:
 1. A signal processing system for light detectionand ranging (LIDAR) operation comprising: an amplifier configured to:receive a plurality of optical signals that are respectively associatedwith a plurality of phases, and generate a plurality of amplifiedoptical signals using the plurality of optical signals; and a splitterthat is coupled to the amplifier, wherein the splitter is configured to:receive the plurality of amplified optical signals, and combine theplurality of amplified optical signals according to the plurality ofphases to generate an optical signal across a plurality of outputs, anamplitude of the optical signal across the plurality of outputscorresponds to a combined amplitude of the plurality of amplifiedoptical signals, and a number of the plurality of amplified opticalsignals is greater than or equal to four.
 2. The signal processingsystem of claim 1, wherein a first phase of the plurality of phases isdifferent from a second phase of the plurality of phases.
 3. The signalprocessing system of claim 1, wherein the plurality of amplified opticalsignals are respectively associated with a common or substantiallycommon amplitude.
 4. The signal processing system of claim 1, whereinthe amplifier comprises a plurality of sub-amplifiers that arerespectively configured to: receive a respective one of the plurality ofoptical signals.
 5. The signal processing system of claim 4, wherein thesplitter comprises a plurality of beam splitters that are respectivelycoupled to a respective one of the plurality of sub-amplifiers, whereinthe plurality of beam splitters are respectively configured to: receivea respective one of the plurality of amplified optical signals.
 6. Thesignal processing system of claim 4, wherein a count of the plurality ofoutputs corresponds to a count of the plurality of sub-amplifiers. 7.The signal processing system of claim 1, wherein the plurality ofoptical signals respectively corresponds to a quasi-continuous wavesignal, wherein the splitter is further configured to: generate acombined optical signal at an output of the plurality of outputs usingthe plurality of amplified optical signals.
 8. The signal processingsystem of claim 7, wherein the splitter is further configured to:combine a first set of out-of-phase signals to generate a first signal;combine a second set of out-of-phase signals to generate a secondsignal; and combine the first signal and the second signal to generatethe combined optical signal.
 9. The signal processing system of claim 7,wherein the splitter is further configured to: remove a plurality ofsignals from other outputs of the plurality of outputs responsive togenerating the combined signal at the output of the plurality ofoutputs.
 10. A light detection and ranging (LIDAR) system comprising: asignal processing system comprising: a phase shifter configured to:receive a plurality of optical signals, and generate a plurality ofphase-shifted optical signals that are respectively associated with aplurality of phases; an amplifier configured to: receive the pluralityof phase-shifted optical signals, and generate a plurality of amplifiedoptical signals using the plurality of phase-shifted optical signals;and a splitter that is coupled to the amplifier, wherein the splitter isconfigured to: receive the plurality of amplified optical signals, andcombine the plurality of amplified optical signal according to theplurality of phases to generate an optical signal across a plurality ofoutputs, an amplitude of the optical signal across the plurality ofoutputs corresponds to a combined amplitude of the plurality ofamplified optical signals, and a number of the plurality of amplifiedoptical signals is greater than or equal to four.
 11. The LIDAR systemof claim 10, wherein a first phase of the plurality of phases isdifferent from a second phase of the plurality of phases.
 12. The LIDARsystem of claim 10, wherein the plurality of amplified optical signalsare respectively associated with a common or substantially commonamplitude.
 13. The LIDAR system of claim 10, wherein the amplifiercomprises a plurality of sub-amplifiers that are respectively configuredto: receive a respective one of the plurality of phase-shifted opticalsignals.
 14. The LIDAR system of claim 13, wherein the splittercomprises a plurality of beam splitters that are respectively coupled toa respective one of the plurality of sub-amplifiers, wherein theplurality of beam splitters are respectively configured to: receive arespective one of the plurality of amplified optical signals.
 15. TheLIDAR system of claim 13, wherein a count of the plurality of outputscorresponds to a count of the plurality of sub-amplifiers.
 16. The LIDARsystem of claim 10, wherein the splitter is further configured to:generate a combined optical signal at an output of the plurality ofoutputs using the plurality of amplified optical signals.
 17. The LIDARsystem of claim 16, wherein the splitter is further configured to:combine a first set of out-of-phase signals to generate a first signal;combine a second set of out-of-phase signals to generate a secondsignal; and combine the first signal and the second signal to generatethe combined optical signal.
 18. The LIDAR system of claim 16, whereinthe splitter is further configured to: remove a plurality of signalsfrom other outputs of the plurality of outputs responsive to generatingthe combined optical signal at the output of the plurality of outputs.19. An autonomous vehicle control system comprising: a signal processingsystem for light detection and ranging (LIDAR) operation comprising: aphase shifter configured to: receive a plurality of optical signals, andgenerate a plurality of phase-shifted optical signals that arerespectively associated with a plurality of phases; an amplifierconfigured to: receive the plurality of phase-shifted optical signals,and generate a plurality of amplified optical signals using theplurality of phase-shifted optical signals; a splitter that is coupledto the amplifier, wherein the splitter is configured to: receive theplurality of amplified optical signals, and combine the plurality ofamplified optical signals according to the plurality of phases togenerate an optical signal across a plurality of outputs, an amplitudeof the optical signal across the plurality of outputs corresponds to acombined amplitude of the plurality of amplified optical signals, and anumber of the plurality of amplified optical signals is greater than orequal to four; and one or more processors configured to controloperation of an autonomous vehicle using the optical signal.